Light emitting diodes (LED), which are semiconductor light emitting devices using nitride semiconductors, have been used for display devices, illumination and the like. Electronic devices using the nitride semiconductors have been used for high-frequency devices and high-power devices.
When such nitride semiconductor device is formed on a silicon (Si) substrate having an excellent mass productivity, a defect and a crack are easily generated due to a difference in lattice constant or thermal expansion coefficient. There is a demand for a technique of producing a high-quality crystal on the silicon substrate. Especially when it is attempted to form a thick n-type GaN layer on the silicon substrate, a crack tends to be generated.